Skateboard Truck With Improved Axle Assembly

ABSTRACT

A truck for use with skateboards and skate devices that includes a novel kingpin assembly that includes a novel axle assembly that is stronger, more durable and lighter than prior art axle assemblies. The truck also has an improved truck hanger that includes a specially designed pocket seat that encourages the tilt-crush bushing of the truck to deform into a plurality of recessed cavities formed in the pocket seat (or plurality of recessed cavities in a novel tilt-crush bushing), thereby more readily absorbing shock and improving the ride quality of the truck. The improved truck hanger also includes uniquely positioned stop pins that function to limit the rotational movement of the truck hanger on the tilt axis during turning maneuvers so as to prevent the wheels from contacting the bottom of the deck and possibly ejecting the rider.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Non-Provisional Application claiming the benefit of co-pendingProvisional Application No. 61/959,725 filed Aug. 29, 2013.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to skateboards and skatedevices, including wheeled scooters. More particularly, the inventionconcerns a truck having a novel axle assembly that is stronger, moredurable and lighter than prior art kingpin assemblies. The inventionalso concerns a truck having an improved truck hanger that includes aspecially designed pocket seat that encourages the tilt-crush bushing ofthe truck to deform into a plurality of recessed cavities formed in thepocket seat thereby more readily absorbing shock and improving the ridequality of the truck. The improved truck hanger also includes uniquelypositioned stop pins that function to limit the rotational movement ofthe truck hanger on the tilt axis during turning maneuvers so as toprevent the wheels from contacting the bottom of the deck and possiblyejecting the rider.

DESCRIPTION OF RELATED ART INCLUDING INFORMATION DISCLOSED UNDER 37 CFR1.97 AND 1.98

Skateboards of various designs having a pair of trucks in opposingorientation disposed under a structural member are well known in theart. The prior art trucks are typically fitted with a pair of wheelswith steering being accomplished by the rider tilting the rider surface,thus pivoting the hangers on a tilt axis between 30 and 55 degrees,rotating axles and wheels in opposite directions, thus causing the boardto turn. The conventional kingpin truck consists of a hanger that tiltson a kingpin assembly mounted approximately perpendicular to the tiltaxis and extending through a central aperture of the hanger with thesteel connecting rod forming the kingpin. The hanger has a centralalignment leg projecting in a transverse direction from the axle thatmaintains the tilt axis and is received by a pivot cup in the mountingbase plate.

The thrust of the present invention is to solve the problems discussedin the preceding paragraphs by providing a uniquely designed truck thatincludes a novel axle assembly that is stronger, more durable, andlighter than prior art axle assemblies. The invention also embodies animproved truck hanger that includes a specially designed pocket seatthat encourages the tilt-crush bushing of the truck to deform into aplurality of recessed cavities formed in the pocket seat, thereby morereadily absorbing shock and improving the ride quality of the truck. Theimproved truck hanger also includes uniquely positioned stop pins thatfunction to limit the rotational movement of the truck hanger on thetilt axis during turning maneuvers so as to prevent the wheels fromcontacting the bottom of the deck and possibly ejecting the rider.

It is to be observed that the lighter a truck, the easier it is totransport and the more it becomes useful for accomplishing various typesof tricks. Unfortunately however, with respect to prior art trucks, alighter truck is a weaker truck. To reduce weight, some manufacturershave introduced axles with hollow center cavities. Though there is aweight savings, the hollow axle does not have the durability of a solidaxle, since a tube of a given diameter and material has at best onlyabout 80%-90% the sheer stress resistance of a solid bar of the samegiven diameter and material. When the skateboard drops off a ledge orlands hard during the performance of a trick, a very high sheer stressis applied through the wheels, then to the inner and outer wheel bearingand finally to the axle. These forces can yield the tubing wall causingit to buckle. Skateboard axles are in reality cantilever structureshaving a portion embedded into the hanger casting and end portions thatare threaded to receive a nut that functions to retain the wheelbearings and wheel. The end portions project from the hanger casting sothat most of the sheer stress is concentrated in the first ⅓ of thecantilever where the inside wheel bearing resides, while the distal endof the axle where the outer wheel bearing resides, bears significantlyless stress. Yet, in prior art truck axles, the diameter and thethickness of the axle is the same at the proximal and distal ends of thecantilever.

The prior art U.S. Publication issued to Shih, No. 2003/0137116,discloses a hanger having a hollow axle, of a constant size, that iscast into a hanger that is lighter than a solid axle of the samediameter. This is a trade-off, as both the hanger and the cantileveredaxle have been weakened for a very modest weight savings.

A conventional skateboard truck hanger is located by the kingpin betweenan upper and lower bushing having sockets recessed in the hanger toreceive the bushings. The lower bushing bears the weight of the riderand is primarily responsible for shock absorption generated from roughroads through elastic deformation. The construction of bushing socketsof prior art hangers has been solid and the lower bushing is received ina pocket located proximate the bottom of the hanger. Since polyurethanedistorts and does not compress, as a load is applied to the bushing, theonly possible area for the bushing to flex is along the outer walls.Because prior art hanger seats are solid, distortion primarily occurs inthe outside wall of the bushing, substantially limiting the shockabsorption potential of the bushing.

Unfortunately, the polyurethane as currently configured does not absorbshock adequately. Urethane does not compress in the same way the rubberbushing used decades-ago did, urethane reacts to applied load bydistorting or bulging. With prior art truck hangers, since the seatpockets are solid, this distortion can only occur in the outside wall ofthe bushing, limiting the shock absorption potential.

Understanding that the ride of previous art was not satisfactory, U.S.Pat. Nos. 6,367,819 and 6,474,666 issued to Anderson teach the use ofadditional lower bushings to help soften the ride. However, in doing so,additional undesirable height and weight is added to the truck assembly.Additionally, additional length is added to the kingpin, therebyincreasing stress on the kingpin assembly. In sharp contradistinction,the skateboard truck of the present invention provides a novelconstruction that allows the skateboard to ride better while using theexisting single lower bushing found in prior art. Accordingly, theskateboard truck of the present invention does not add any additionalcost to the truck.

U.S. Pat. No. 7,093,842 to Chemlar, discloses a means for limiting therotation of the hanger when turning. However, in Chemlar, this means ispositioned so close to the pivot axis that a severe leveragedisadvantage results which is readily apparent during a hard turningmaneuver or when landing a jump.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a truck for use withskateboards and skate devices that includes a novel axle constructionwhich comprises an axle that has greater wall thickness in areas of highstress and lesser wall thickness in areas of lower stress.

Another object of the invention is to provide a kingpin assembly of thecharacter described in the preceding paragraph in which the diameter ofthe axle at the inner bearing area is larger than the axle diameter atthe outer bearing area.

Another object of the invention is to provide an improved truck hangerthat includes a specially designed pocket seat that encourages thetilt-crush bushing of the truck to deform into a plurality of recessedcavities formed in the pocket seat, thereby more readily absorbing shockand improving the ride quality of the truck.

Another object of the invention is to provide a kingpin assembly of thecharacter described that includes a novel tilt-crush bushing having aplurality of recessed cavities into which the bushing can deform whenplaced under load.

Another object of the invention is to provide an improved truck hangerthat includes stop means for limiting rotational movement of the truckhanger on the tilt axis during turning maneuvers so as to prevent thewheels from contacting the bottom of the deck and possibly ejecting therider.

Another object of the invention is to provide a truck that is durable,safe, and highly reliable in operation.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a front view of one form of the skateboard truck of theinvention.

FIG. 1A is a generally perspective view, partly in cross-section, of theform of the skateboard truck shown in FIG. 1 as it appears when mountedon a structural member.

FIG. 1B is an enlarged, cross-sectional view of one form of the axle ofthe skateboard truck of the invention.

FIG. 1C is an enlarged, cross-sectional view of an alternate form ofaxle of the skateboard truck of the invention.

FIG. 1D is an enlarged cross-sectional view taken along lines 1D-1D ofFIG. 1.

FIG. 2A is a cross-sectional view of still another form of axle of theskateboard truck of the invention.

FIG. 2B is a cross-sectional view of yet another form of axle of theskateboard truck of the invention.

FIG. 2C is a cross-sectional view of still another form of axle of theskateboard truck of the invention.

FIG. 3 is a fragmentary, illustrative cross-sectional view illustratingthe appearance of the device when no load force is applied to thedevice.

FIG. 3A is a greatly enlarged cross-sectional view of the areadesignated in FIG. 3 as 3A.

FIG. 4 is a fragmentary, illustrative cross-sectional view similar toFIG. 3 illustrating the direction of load force applied to the deviceand illustrating the manner of deformation of the tilt bushings.

FIG. 4A is a greatly enlarged cross-sectional view of the areadesignated in FIG. 4 as 4A.

FIG. 5 is a greatly enlarged, generally perspective, exploded view ofone form of the hangar assembly of the invention.

FIG. 6 is an enlarged, generally perspective view of a typical prior artbushing.

FIG. 7 is an enlarged, generally perspective view of one form of thenovel bushing of the present invention.

FIG. 7A is a side view of the tilt bushing shown in FIG. 7 as it appearsunder no load.

FIG. 7B is a greatly enlarged view of the area designated in FIG. 7A as7B.

FIG. 8 is a side view of the tilt bushing shown in FIG. 7 as it appearsunder load and illustrating the manner of deformation of the tiltbushing.

FIG. 8A is a greatly enlarged view of the area designated in FIG. 8 as8A.

FIG. 9 is a generally perspective view of yet another form of theskateboard truck as it appears when mounted on a structural member.

FIG. 9A is a greatly enlarged view of the area designated in FIG. 9 as9A.

FIG. 10 is a generally perspective view of an alternate form of the baseassembly of the skateboard truck.

FIG. 11 is a generally perspective view of still another form of thebase assembly of the skateboard truck.

FIG. 12 is a generally perspective view of yet another form of the baseassembly of the skateboard truck.

FIG. 12A is a greatly enlarged, exploded view of the stop pin holdingbracket of the assembly shown in FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings and particularly to FIGS. 1 and 1A, one formof the truck of the invention is there shown and generally designated bythe numeral 12. As will become clear from the description that follows,the truck of the invention is usable with a skateboard, a scooter, andlike vehicles of the character having a structural member 15, such as adeck upon which the truck can be mounted. Truck 12 here comprises a baseassembly 17 that is connected to the structural member 15 and a kingpinassembly 18 that is connected to base assembly 17. Truck 12 alsoincludes a novel hanger assembly 20 that is interconnected with thekingpin assembly. Hanger assembly 20 here includes a transverselyextending axle 21 to which a pair of wheels “W” is rotatably mounted ina conventional manner well known to those skilled in the art (only onewheel is shown in FIGS. 1 and 1A of the drawings).

Axle 21 is of the unique construction shown in FIG. 1B and includes acentral portion 21 a, a pair of end portions 21 b, and a pair ofintermediate portions 21 c. Intermediate portions 21 c here define theinner bearings 22 of the axle. While the axle can be formed in variousways, it is preferably constructed by swaging a length of metal tubingto form an axle of the character shown in FIG. 1B having central portion21 a of a first diameter, a pair of end portions 21 b of a second lesserdiameter, and a pair of intermediate portions 21 c of a third diameterthat is greater than the second diameter but less than the firstdiameter. For a reason presently to be described, central portion 21 aincludes an inwardly curved recess 24.

As shown in FIGS. 1 and 1B, intermediate portions 21 c of the axle 21carry inside wheel bearings 32, while the threaded end portions 21 bcarry outside wheel bearings 33. Bearings 32 and 33 support wheels “W”and conventional axle nuts 30 function to hold the bearings and wheelsin place.

Turning to FIG. 1C, an alternate form of axle is there shown andgenerally designated by the numeral 35. Axle 35, which is constructed ina different manner than axle 21, comprises first and second metalportions 35 a and 35 b that are welded together at the parting line 35c. Axle 35 is of the unique construction shown in FIG. 1C and includes acentral portion 36 a, a pair of end portions 36 b and a pair ofintermediate portions 36 c. Intermediate portions 36 c here define theinner bearings of the axle, while end portions 36 b define the outerbearings of the axle. Axle 35 can be formed in various ways, but it ispreferably constructed by boring out the central portions of each of thefirst and second portions 35 a and 35 b to form hollow segments 40 andby boring out the end portions of each of the first and second portions35 a and 35 b to form hollow segments 41. Following the boring step, thefirst and second axle portions 35 a and 35 b are welded together and thecentral portion is embossed to form inwardly curved recess 42 thataccepts the kingpin assembly. As in the earlier described axle 21, axle35 has a central portion 35 d of a first diameter, a pair of endportions 35 e of a second lesser diameter, and a pair of intermediateportions 35 f of a third diameter that is greater than the seconddiameter but less than the first diameter. As before, intermediateportions 35 f of the axle 35 carry inside wheel bearings 32, while thethreaded end portions 35 e carry outside wheel bearings 33. Bearings 32and 33 support wheels “W” and conventional axle nuts 30 function to holdthe bearings and wheels in place. As indicated in FIG. 1C, the wallthickness of the inside wheel bearings, or intermediate portions 35 fwhere the sheer forces of an applied load are the greatest, are of afirst wall thickness. On the other hand, the outside wheel bearings orend portions 35 e, where less sheer forces are less, are of a secondwall thickness, less than the first wall thickness.

In one form of the invention, the axle protruding from the casting toreceive a wheel begins as a larger diameter for receiving an insidewheel bearing where the sheer forces of an applied load are greatest,then reducing to a smaller standard diameter for the outside bearingwhere sheer forces are less. FIG. 1D illustrates the cross- sectionalappearance of the casting and the axle that protrudes therefrom.

Referring now to FIGS. 2A, 2B and 2C, a plurality of alternate forms ofaxle constructions are there shown. More particularly, FIG. 2A shows anaxle construction in which the central portion of the axle is generallyrectangular in cross-section, FIG. 2B shows an axle construction inwhich the central portion of the axle is generally oval incross-section, and FIG. 2C shows an axle construction in which thecentral portion of the axle is generally triangular in cross-section.

In forming the hanger assembly 20 of the invention, a selected one ofaxle 21, or axle 35, is cast into the hanger barrel 46 a to form theconstruction illustrated in FIG. 1. As best seen in FIG. 1A, connectedto the hanger barrel 46 a and extending therefrom is a generallytriangular shaped kingpin connector 46 b to which the highly importantkingpin assembly 18 is connected. The kingpin assembly 18 here comprisesa connecting rod 39 having a trunk portion 39 a and a head portion 39 b.Connected to the trunk portion 39 a of connecting rod 39 are first andsecond tilt-crush elastic bushings 48 a and 48 b. The function of thesetilt-crush elastic bushings will be described in the paragraphs whichfollow.

As seen in FIG. 3, hanger assembly 20 also includes a central alignmentleg 46 c that projects in a transverse direction from barrel 46 a.Alignment leg 46 c, the distal end of which is received in a pivot cup47 that is formed in base assembly 17 (FIG. 1A), functions to maintainthe tilt axis of the skateboard.

The connecting rod 39 of the kingpin assembly 18 can be described instructural terms as a cantilevered beam with the fixed end beingattached to the base plate member and a free end protruding outwardlytherefrom. When a force is placed at the free end of the cantileveredbeam, sheer stresses are unequally distributed along the length of thebeam with the greatest magnitude of stress concentrated at the fixedpoint and the least amount of stress being located at the free end.

Additionally, the fixed end of the connecting rod is subjected tosubstantial tensile stresses. For example, as the hanger tilts forsteering, stress is applied to the fixed end of the connecting rod asthe hanger pries the two tilt-crush bushings apart using the connectingrod as a fulcrum. The energy stored during this compression of thetilt-crush bushings returns the hanger back to a neutral steeringposition.

Considering now the function of the tilt-crush elastic bushings 48 a and48 b of the present invention, in a conventional prior art skateboard,the lower polyurethane bushing bears the weight of the rider and isprimarily responsible for shock absorption generated from rough roadsthrough elastic deformation. The construction of the bushing sockets ofthe prior art hangers is typically solid and the lower bushing seats ina pocket formed proximate the bottom of the hanger. Because polyurethaneand urethane does not compress, but only distorts, as load is applied tothe bushing, the only area possible for the bushing to flex is along theouter walls of the bushing, thereby limiting the shock absorptionpotential of the bushing. As best seen in FIG. 5 of the drawings, thetruck hanger of the present invention includes cup washers 49 a and 49 bthat receive bushings 48 a and 48 b respectively. The truck hanger alsoincludes the specially designed pocket seat 47 that comprises aplurality of circumferentially spaced ribs 52 that define a plurality ofcircumferentially spaced cavities 54. With this novel construction, asload is applied to the lower tilt bushing 48 b in the direction of thearrow 56 of FIG. 4, the lower tilt bushing will be encouraged to bulgeinto recessed cavities 54 and between the seat pocket ribs 52 asindicated by the lines 58, thereby encouraging movement, more readilyabsorbing shock and significantly improving the ride quality of thetruck.

Referring to FIG. 7, this figure drawing illustrates an alternate formof lower bushing of the present invention, which is identified as 48ALT.Unlike the upper surface “U” of the prior art bearing shown in FIG. 6 ofthe drawings, the upper surface of this bearing is provided with aplurality of circumferentially spaced ribs 52ALT that define a pluralityof circumferentially spaced cavities 54ALT (see also FIGS. 7A and 7B).With this novel construction, as load is applied to the bushing in thedirection of the arrow 56ALT of FIG. 8, the upper tilt bushing will beencouraged to bulge into recessed cavities 54ALT and between the ribs52ALT as indicated by the lines 58ALT, thereby encouraging movement,more readily absorbing shock, and significantly improving the ridequality of the truck (see also FIG. 8A).

Another novel feature of the hanger of the present invention is theprovision of stop means for limiting the rotational movement of thehanger on the tilt axis during turning maneuvers so as to prevent thewheels “W” from contacting or biting into the bottom of the deck 15 andpossibly ejecting the rider. This important stop means here comprises aplurality of stop pins 60 that are threadably connected to and extendfrom the kingpin connector 46 b (FIGS. 5 and 9). As illustrated in FIGS.6 and 9A, with this construction, as the hanger tilts on the tilt axisin the manner indicated by the arrow 61, the distal ends 60 a of thestop pins 60 will engage the base assembly 17 and prevent the wheels “W”from contacting the bottom of the deck 15. The extent to which the stoppins 60 extend from kingpin connector 46 b can be adjusted by tighteningand loosening the pair of lock nuts 60 b.

Turning to FIG. 10, an alternate form of the base assembly 63 of theskateboard truck is there shown. In this form of the invention, the stoppins 60 are mounted on a pair of generally angularly extending faces 64so that the pins extend angularly outwardly from the base assembly.

In FIG. 11, there shown is a generally perspective view of still anotherform of the base assembly of the skateboard truck 66 in which the stoppins 60 are mounted on a pair of outwardly-extending ears 67 formed onthe base assembly.

Turning to FIG. 12, yet another form of the base assembly of theskateboard truck 70 is shown in which the stop pins are mounted on aholding bracket 72 which, in turn, is mounted proximate the upperportion of the base assembly. FIG. 12A is an enlarged, exploded view ofthe stop pin holding bracket 72 of the assembly shown in FIG. 9, showingthe manner in which the stop pins are threadably interconnected with aholding bracket.

Having now described the invention in detail in accordance with therequirements of the patent statutes, those skilled in this art will haveno difficulty in making changes and modifications in the individualparts or their relative assembly in order to meet specific requirementsor conditions. Such changes and modifications may be made withoutdeparting from the scope and spirit of the invention, as set forth inthe following claims.

1. A truck for a skateboard, scooter and the like, having a structuralmember, said truck comprising: (a) a base assembly connected to thestructural member; (b) a kingpin assembly connected to said baseassembly; (c) a hanger assembly connected to said kingpin assembly, saidhanger assembly including an axle having a central portion of a firstdiameter, a pair of end portions of a second lesser diameter and a pairof intermediate portions of a third diameter greater than said seconddiameter and less than said first diameter; and (d) a pair of wheelsrotatably mounted on said axle.
 2. The truck as defined in claim 1 inwhich said axle has intermediate portions of a first wall thickness andend portions of a second, lesser wall thickness.
 3. The truck as definedin claim 1 further including inside wheel bearings mounted on saidintermediate portions of said axle.
 4. The truck as defined in claim 1further including outside wheel bearings mounted on said end portions ofsaid axle.
 5. The truck as defined in claim 1 in which said axle isformed by swaging a length of metal tubing.
 6. The truck as defined inclaim 1 in which said central portion of said axle is generallyrectangular in cross-section.
 7. The truck as defined in claim 1 inwhich said central portion of said axle is generally oval incross-section.
 8. The truck as defined in claim 1 in which said centralportion of said axle is generally triangular in cross-section.
 9. Thetruck as defined in claim 1 in which said kingpin assembly comprises aconnecting rod having a trunk portion and a head portion and atilt-crush elastic bushing connected to said trunk portion of saidconnecting rod.
 10. The truck as defined in claim 9 in which said hangerassembly comprises a hanger barrel and a kingpin connector connected tosaid hanger barrel, said kingpin connector being provided with a pocketseat having a plurality of circumferentially spaced ribs that define aplurality of circumferentially spaced cavities, said pocket seat beingso constructed and arranged to receive said tilt-crush elastic bushing.11. A truck for a skateboard, scooter and the like, having a structuralmember, said truck comprising: (a) a base assembly connected to thestructural member; (b) a kingpin assembly connected to said baseassembly, said kingpin assembly comprising a connecting rod having atrunk portion and a head portion and a tilt-crush elastic bushingconnected to said trunk portion of said connecting rod; (c) a hangerassembly connected to said kingpin assembly, said hanger assemblycomprising: (i) a hanger barrel; (ii) an axle carried by said hangerbarrel; (iii) a kingpin connector connected to said hanger barrel, saidkingpin connector being provided with a plurality of stop pins connectedto and extending from said kingpin connector; and (d) at least one wheelrotatably mounted on said axle.
 12. The truck as defined in claim 11 inwhich said axle has a central portion of a first diameter, a pair of endportions of a second lesser diameter and a pair of intermediate portionsof a third diameter greater than said second diameter and less than saidfirst diameter.
 13. The truck as defined in claim 11 in which said baseassembly includes a base having a pivot cup and in which said hangerassembly further includes a central alignment leg receivable within saidpivot cup.
 14. The truck as defined in claim 11 further including apocket seat having a plurality of circumferentially spaced ribs thatdefine a plurality of circumferentially spaced cavities, said pocketseat being so constructed and arranged to receive said tilt-crushelastic bushing.
 15. The truck as defined in claim 11 in which saidkingpin assembly further includes a second tilt-crush elastic bushingconnected to said trunk portion of said connecting rod.
 16. A truck fora skateboard, scooter and the like, having a structural member, saidtruck comprising: (a) a base assembly connected to the structuralmember, said base assembly including a base having a pivot cup; (b) akingpin assembly connected to said base assembly, said kingpin assemblycomprising a connecting rod having a trunk portion and a head portionand first and second tilt-crush elastic bushings connected to said trunkportion of said connecting rod; (c) a hanger assembly connected to saidkingpin assembly, said hanger assembly comprising: (i) a hanger barrel;(ii) an axle carried by said hanger barrel, said axle havingintermediate portions of a first wall thickness and end portions of asecond, lesser wall thickness; (iii) a kingpin connector connected tosaid hanger barrel, said kingpin connector being provided with a pocketseat having a plurality of circumferentially spaced ribs that define aplurality of circumferentially spaced cavities, said pocket seat beingso constructed and arranged to receive a selected one of said tilt-crushelastic bushing; and (d) a pair of wheels rotatably mounted on saidaxle.
 17. The truck as defined in claim 16 in which said hanger assemblyfurther includes a central alignment leg receivable within said pivotcup of said base assembly.
 18. The truck as defined in claim 15 furtherincluding a plurality of stop pins connected to and extending from saidkingpin connector.
 19. The truck as defined in claim 15 in which saidhanger assembly further comprises a pair of cup washers carried by saidconnecting rod of said kingpin assembly, said pair of cup washers beingso constructed and arranged to receive said first and second tilt-crushelastic bushings.
 20. The truck as defined in claim 15 in which saidcentral portion of said axle includes an inwardly curved recess.